Catching a cold is almost a rite of passage for the chilly winter months when people and viruses are often in close quarters. And that’s especially true among children, who aren’t stingy about what they share among friends and loved ones when it comes to viral stowaways. And while most youngsters shake off the sniffles after a few days, a new study suggests the legacy of some of those bouts with a cold may be making our children obese.

Dr. Jeffrey Schwimmer, a pediatrician at University of California San Diego, found that in a study of 124 children aged 8 to 18, youngsters with evidence of an antibody to a common cold virus were three times more likely to be obese that those without the antibody. The antibody is a molecular remnant of an infection with a virus. What’s more, Schwimmer’s team also learned that among overweight and obese children, those with the antibody were on average 35 pounds heavier than those without the immune marker.

“What this points to is a virus causing accumulation of body fat, which is causing weight gain that is specifically fat gain,” he says. And that can tremendously increase the risk that a child will have additional health problems.” (More on Time.com: See a special report on overcoming obesity)

Schwimmer notes that the weight gain recorded among the children who had been infected with the virus was almost exclusively in the form of fat. And that may have to do with the way this particular virus acts on the body. While there are about 50 different forms of cold viruses, so far this one strain is the only one that has been associated with weight gain. In animal tests and experiments on human cells in the lab, says Schwimmer, this virus shows a particular preference for infecting fat cells and their precursors. Once inside, the virus can rev up the cell’s development cycle, causing immature fat cells to mature more rapidly and generate more fat cells, or pushing fat cells to divide more and become plumper and larger. “All of these studies suggest that the virus can produce both a greater number of fat cells and make each and every fat cell larger to store more fat,” he says.

If the finding is confirmed, it won’t be the first link between a seemingly unrelated infection and a chronic disease. Researchers now know that the majority of stomach ulcers are caused by the bacteria H. pylori, while many cervical cancers can also be traced to infection with human papillomavirus. The latest studies also suggest that heart disease may in part be due to inflammation in response to oral bacteria that enter the bloodstream. (More on Time.com: The ‘Other’ Salt: 5 Foods Rich in Potassium)

Schwimmer’s study, however, doesn’t necessarily mean that every new cold will cause a child to pack on the pounds. It’s not clear yet how common this particular cold virus is, nor is it obvious how important a role these infections play in the complicated regulation of body weight. People are also likely to have varying degrees of susceptibility to the effects of this virus on their fat metabolism. “This is a factor, but it’s not going to be the factor in understanding obesity,” he says. But it highlights the importance of some easy preventive health measures, just in case, that many children take for granted—washing hands and covering coughs and sneezes to avoid catching a cold in the first place.